In recent years a demand has arisen for silver halide sensitive materials, and especially camera color sensitive materials, which have excellent graininess and sharpness at high photographic speed and which also have excellent de-silvering properties as typified by ISO speed 100 and ISO speed 400 sensitive materials which have a high image quality (Super-HG-400).
Methods in which photographically useful groups are bonded to the coupling position of a coupler via a timing group and in which the photographically useful groups are released imagewise at the appropriate time during development processing are known as an elementary means of improving image quality. Examples of these methods have been disclosed in U.S. Pat. No. 4,409,323 and JP-A-60-218645. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application".)
The methods of these disclosures involve the release of one molecule of photographically useful group from one molecule of coupler.
However, when these couplers are added in large amounts to a film of a photosensitive material, the film's thickness is increased, sharpness becomes poorer and the cost is increased.
Furthermore, couplers which release two molecules of a photographically useful group from one carbon atom on a timing group have been proposed in JP-A-1-154057. But as a result of their inter-layer effect, these couplers do not provide satisfactory color reproduction, and improvement of the side absorptions of the colored dyes is required.
Pyrazolotriazole type magenta couplers which have little side absorption have been suggested as such couplers in JP-B-47-27411 for example, and they do provide the desired color reproduction, but it has still not been possible to achieve truly satisfactory color reproduction. (The term "JP-B" as used herein signifies an "examined Japanese patent publication").
Attempts have been made to achieve remarkable effects by using combinations of the techniques outlined above instead of using these techniques individually.
For example, combinations of pyrazoloazole based magenta couplers and various development inhibitor releasing couplers (compounds) have been suggested in JP-A-60-262158, JP-A-62-151850, JP-A-63-74058, JP-A-64-77056 and JP-A-1-251032. Some beneficial effect has been achieved, but a satisfactory level of graininess, sharpness, color reproduction and de-silvering properties has not been achieved.
Furthermore, combinations of so-called timing DIR couplers and bleaching accelerator releasing compounds have been suggested, for example, in JP-A-63-216048, JP-A-2-39146, JP-A-2-44338 and JP-A-2-44339. There is some improvement in color reproduction, de-silvering properties, graininess and sharpness, but they are still not satisfactory.
Moreover, the development inhibitor releasing couplers (compounds) disclosed in the patented combinations described above only release one molecule of a development inhibitor from one molecule of compound. Further, they have to be added in large amounts and there is also a problem in that the cost is high.